Gaseous fluid relays



Sept. 13, 1955 Filed July 12, 1951 R. LEROUSSEAU ET AL GASEOUS FLUIDRELAYS 5 Sheets-Sheet l pt 13, 19 R. LEROUSSEAU ET AL 2,717,611 IGASEOUS FLUID RELAYS Filed July 12, 1951 5 Sheets-Sheet 2 56 7 as"III/II 37 n/M v W p 13, 1955 R. LEROUSSEAU ETAL 2,717,611

GASEOUS FLUID RELAYS Filed July 12, 1951 5 Sheets-Shed s ErrUIIIIIIIIIIIIA 5 55 J;

Sept 1 1 R. LEROUSSEAU ET AL 2,717,611

GA'sEous FLUID RELAYS Filed July 12, 1951 5 Sheets-Sheet 4 Sept. 13,1955 Filed July 12, 1951 R. LEROUSSEAU ET AL GASEOUS FLUID RELAYS 5Sheets-Sheet 5 gdw y United States Patent GASEOUS FLUID RELAYS RobertLerousseau and Georges Bourdeau, Paris, France,

assignors to Regulateurs Francel, Paris, France, a corporation of FranceApplication July 12, 1951, Serial No. 236,416

Claims priority, application France July 21, 1950 Claims. ((31. 137-85)The present invention relates to gaseous liuid relays of the typedescribed in French Patent No. 954,055 filed September 25, 1947, whichcomprises, as a fundamental means, a nozzle through which a gaseousfluid jet is released, cooperating with a shutter, or movable screenlocated in the path of said jet, and with a movable surface the positionof which, with reference to the nozzle, determines the air pressure insaid nozzle, the variations of said pressure being amplifiable forvarious purposes.

According to the above-mentioned French patent, the shape of the nozzleis such that the contracted region of the fluid jet is located withinthe nozzle or, at least, in the plane of the output section of thismember. Such an arrangement already gives interesting results, as far asthe sensitiveness and accuracy of operation of said device areconcerned. v

However, it was found possible to still increase this sensitivenesswithout lowering the fidelity and even increasing it, which resulted inproviding a use for various purposes, by means of extremely reducedforces, of the variations of a phenomenon, even when said variationshave a very small amplitude and a very weak self-power.

The object of the present invention is a modification of theabove-mentioned fundamental means, which modification gives the resultsset forth, principally by giving said fundamental means an extremelyincreased sensitiveness, without lowering in any way its fidelity, themeans thus modified being possibly cornbinable with an emplifyingdevice, the variations of which are practically instantaneous and themultiplication factor of which is particularly increased.

The modification of the above-mentioned means fundamentally consists, onthe one hand, in giving the gaseous fluid jet the shape of a jetcontracted at the outside of the nozzle, for instance through shapingthe outlet orifice of the nozzle as a thin walled orifice and, on theother, in simultaneously locating the shutter-screen in the contractedzone obtained, preferably at the place of maximum contraction, saidshutter-screen, either at right angle or at a different angle to thefluid jet, being made movable and being moved depending upon conditions,either parallel or at an angle to itself, under the action of thevariable phenomenon.

This arrangement does away with the necessity existing in theabove-cited devices of adjusting the nozzle in a very precise mannerrelatively to the nozzle, which results in the suppression of a deadtorque reducing the sensitiveness.

Moreover this arrangement allows a sensitive element to act directly onthe nozzle, even if the respective displacements of the nozzle andscreen, within certain relatively broad limits, are not parallel to oneanother.

On the other hand, since it is unnecessary to completely obturate thenozzle in order to submit the screen to the action of all partial jetsof which the main jet is formed, said arrangement also allows to move,before the nozzle and in a frictionless manner, a screen driven by anelement with reduced torque, to which will be opposed only 2,717,51 iPatented Sept. 13, 1955 the kinetic energy of the fluid jet, whichenergy is entirely under control, because of the low pressure which issulficient for operating the relays intended to amplify the forcedisplacing the screen which modulates the pressure within the nozzle.

Such a device may be combined, for example, with amplifying relaysand/or servo-motors, with indicating, registering, repeating, orregulating devices.

Further features of the invention will appear from the followingdescription, with reference to the appended drawings, diagrammaticallyillustrating various embodiments of the present invention, and in which:

Figs. 1, 2 and 3 are large scale diametrical sections of nozzles such asembodied in the device described in the above-mentioned patents;

Fig. 4 is a similar view of a nozzle according to the present invention;

Fig. 5 is a view, similar to Fig. 4, embodying an arrangement of thenozzle shown in Fig. 4 in cooperation with an orientable screen;

Fig. 6 is a perspective view, with parts broken away, a first embodimentof the invention;

Fig. 7 is a diagrammatic View of a second embodiment of the invention,with an associated servo-motor device;

Fig. 8 is a similar view of a further embodiment;

Fig. 9 is a view similar to that shown in Fig. 7, relating to a furtherapplication of the invention;

Fig. 10 is also a view similar to Fig. 7, relating to a fifthmodification;

Fig. 11 shows diagrammatically a sixth embodiment;

Fig. 12 shows a seventh modification, relating to applications of theinvention for indicating, registering and rejecting purposes, and

Fig. 13 is a plan view of a portion of the same.

In the embodiment shown in Fig. 1, a nozzle 1 cooperates with a screen 2carried on a resilient blade 3 fixed on the same support 4 as saidnozzle. If an air jet issued from a container (not shown) of relativelyreduced effective capacity and low pressure uniformly fed withcompressed air, is blown through nozzle 1 towards screen 2, acontraction of said air jet is produced, in plane A-A, upstream toorifice 5 of said nozzle. The latter, however, spreads downstream toorifice 5 and, in such a condition impinges on screen 2, on which itexerts a certain pressure. The latter is counteracted by spring 3 whichis bent. The screen assumes a balance position and the pressure withinand behind the nozzle takes a determined value. If, by any suitablemeans, the position of screen 2 with relation to orifice 5 of the nozzleis varied, for example by being shifted to the left of the drawing, bymeans of a stop 8, a key 7 carried on screen 2, the screen will bebrought nearer to orifice 5 and the air pressure within nozzle 1 willincrease. If, on the other hand, while stop 8 is left behind in itsinitial position shown in Fig.v 1, the air pressure within nozzle 1 isincreased, screen 2 will be pushed away (against the action of spring 3which is bent) and meets stop 8 in its new position, air will escapemore easily through nozzle 1 and the pressure will decrease Within thelatter, until a new balance condition is obtained, and so on, wheneverstop 8 is moved forward or backward. From the relative position of stop8 and orifice 5 thus depends the pressure within the nozzle andconsequently within the tank located upstream to said nozzle. Variationsof the distance from the stop to orifice 5 of the nozzle are obtained,for instance, by displacing stop 8 parallel to itself towards thenozzle, or by giving said stop an angle with reference to the directionof the air jet and displacing said stop parallel to itself and obliquelyto the direction of the jet.

Similar effects are produced when using, instead of a nozzle withcylindrical inner bore such as shown at. 1 in Fig. 1, a convergingnozzle such as shown in Fig. 2,

and the convergency angle a of which is larger than that b of the airjet within the nozzle. In such a case, the gaseous jet leaves the innerwall of the nozzle and the maximum concentration zone of the air jet isin plane A--A of outlet orifice of the nozzle.

If a bi-cylindrical nozzle is used, such as shown at 11, 12, in Fig. 3,with a wide angled separating shoulder 13 therebetween, maximumconcentration zone AA will be located within cylindrical portion 12. Inthe three latter cases, the gaseous jet expands beyond the outletorifice of the nozzle and the gaseous jets meeting a screen such as 2 inFig. 5, impinge on it in a spreaded shape.

If however, according to the invention, the nozzle through which the airjet is projected, is formed in such a manner that outlet orifice 14 ofsaid nozzle (Fig. 4) is formed in a thin end wall 16 substantiallyperpendicular to the axis of the nozzle, the orifice 14 beingsubstantially smaller in diameter than the wall 16. With suchconstruction the gaseous jet will leave internal wall 17 of the nozzleand the maximum contraction zone A-A of the air jet will be locateddownstream and at a certain distance of said orifice 14. Screen 2 is tobe located within this maximum contraction zone of the air jet. In thisposition the gaseous jets are quite concentrated, contrarily to whathappens in the case of the nozzle devices of Figs. 1, 2 and 3. Theimpact zone is more reduced and therefrom results at this point aconcentration of energy which increase the sensitiveness and fidelity ofthe device. These qualities attain a maximum when the face of the screenreceiving the air jet is located within the maximum contraction zone ofthe air jet, as shown in Fig. 5.

Such a nozzle with thin-walled orifice is well adapted to angulardisplacements which it may be necessary to give screen 2 (as, forinstance, positions 2a, 2b) by rotating the latter about an axis ofrotation 18, at right angle to the geometrical axis of the air jets.

On the other hand, the combination of screen 2, key 7 and stop 8,diagrammatically shown in Fig. 1 may be reduced, according to onefeature of the invention, to a single screen, the face of which nearerto the nozzle is formed as a cam and is moved in such a manner that thedistance between the nozzle and the point at which the air jet impingeson the latter is varied, thus varying the air pressure behind thenozzle. This particular embodiment is shown in Figs. 6 to 12.

There may thus be provided such a device providing a nozzle the outletorifice 14 of which, forming a thin walled orifice, has ahalf-millimeter (0.5 mm.) diameter, and in which screen 2, located at0.2 mm. distance from said U orifice 14, receives a thrust of twodecigrarns per square centimeter (0.2 gr. per cm?) and consequently canbe moved by means of an extremely reduced force. The variations of theair pressure behind the nozzle (herein called modulated pressure) may beamplified at will and may serve to obtain any desired slave orindependent control, with or without using servo-motors.

For instance, by forming the screen as an end cam 19 (Fig. 6) mounted onthe axis of a galvanometer 20 and opposite the upper section 21 of whichis located a nozzle 22, fed with compressed air and the orifice ofwhich, formed as a thin walled orifice, directs a thin air jet on cam21, and by giving said cam a height decreasing from 24 to through 21according to a predetermined law, the rotation of the cam will cause avariation, according to said law, of the distance between orifice 23 ofthe nozzle and cam 21, thus varying, according to the same law, the airpressure behind the nozzle. Since small variations of the distancebetween the cam and the nozzle provide large variations of saidpressure, the maximum height variations of cam 21 from 24 to 25 may besmall, thus remaining within the concentration zone of the air jet; Witha 0.5 mm. nozzle orifice and an air pressure of 0.2 gram per squarecentimeter at the outlet of said orifice, a power of one quarter of amilliwatt is suificient to produce behind the nozzle pressuremodulations which can be almost instantaneously amplified up to adesired number of tons.

The nozzle may be made movable, when it is desired to obtain an airpressure, determined at every instant, as a function of the position ofan element indicating the condition of a phenomenon. Fig. 7 shows such adevice in which 24 is a member fastened at one end 25 to a fixed support26 and which is deformable as a function of an inner pressure varyingaccording to temperature, and the variations of which are intended tomodulate the air pressure within nozzle 31, submitted to the displacements of an arm 35. Element 24 rotates, around a fixed shaft 23, bymeans of a connecting rod 29, a screen 30 located opposite the orificeof a nozzle 31, fed with air through fixed duct 27 and flexible hose 32,the distance from said screen to the nozzle orifice being chosen so thatsaid screen remains in the contraction zone of the air jet issuing fromnozzle 31 for all positions which end 33 of indicator 24- can assume.The nozzle is fixed to arm 34 of a bell crank lever 34, 35 pivoted on ashaft 36, fixed on a support 37. One end of arm 35 leans on push rod 38of bellows 39 connected to pipe 40 which itself is connected to hose 32.A throttling valve 41 is used to regulate the air pressure at nozzle 31and bellows 39.

Air flowing through duct 27 under a pressure regulated by throttle valve41 being admitted into pipe 40, an air jet flows out through nozzle 31and a determined pressure is established in the assembly 31, 32, 40, 39as a function of the position of screen 30 corresponding to a determinedcondition of element 24. The air pressure within bellows 39 moves thenozzle away from the screen through the agency of bell crank lever 35,34, until a balance position is attained due to screen 30 reacting onthe air jet flowing out of the nozzle. By adjusting the air feedpressure by means of valve 41, the nozzle is caused to assume such aposition that the distance from its orifice to the active face of screen30 be the position for which said face is located within the maximumcontraction zone of the air jet from the nozzle.

If, due to a variation in the phenomenon determining the shape ofelement 24, end 33 of the latter drives screen 30 and the nozzle furtherapart from one another, the effect of the reaction thrust of the air jeton the screen decreasing due to this separation, results in a decreaseof the pressure within ducts 32 and 40 and in bellows 39 which collapse.Push rod 38 is lowered, arm 35 follows, and arm 34 drives nozzle 31nearer to screen 30, until the reaction of the air jet on the screenincreases the reaction thrust of the air jet on the nozzle and drivesthe latter to a new balance position corresponding to the deformation ofthe above-mentioned element and thus to a new condition of thetemperature the variations of which are to be observed.

A variation in the opposite direction of the condition of saidphenomenon producing, in another direction, modifications of thescreen-nozzle assembly would drive back the bell-crank lever and bellowsand a new balance would be established, corresponding to the newcondition of the phenomenon.

It must be appreciated that the displacements of nozzle 31 and screen 30may be non-parallel without the sensitiveness and operational accuracyof the device being affected, as the portions of both these elementswhich are concerned with the contracted zone of the air jet may describelarge radius circumferences which are either tangent or slightly secant.

The visible or audible temperature indication is obtained by controllingthrough arm 35 any suitable apparatus adapted to give such indicationsunder the effect of the displacements of arm 35. v

Fig. 8 relates to cases in which it is desired, as with relation to Fig.7, to translate into indications a registering or regulation of quitesmall intensity variations of an electric current, which itself is verysmall. In Fig. 8, nozzle 42, with a thin Walled orifice, is solid withan arm 43 pivoted on a shaft 44 solid with a fixed support 45. At normalposition, nozzle 42 is at such a distance from the end edge 46 of a cam47 that said edge is within the contraction zone of the air jet flowingout of the nozzle. Said cam 47 is solid with the moving frame of agalvanometer 48. In order to insure said distance, arm 43 rests onpush-rod 49 of the movable member 50 of a capsule 51. Nozzle 42 andcapsule 51 are fed with air under pressure through respective ducts 52and 53, connected to an air feeder 54, in which is interposed aregulating valve 55.

The operation of the device shown in Fig. 8 is the same as that of thedevice shown in Fig. 7, obvious modifications being taken into account.If the system is supposed to be mechanically and aerodynamicallybalanced, for a given pressure of the feed air and for a given currentflowing through the galvanometer, that is if cam 47 occupies an angularposition corresponding to said current, if, moreover, nozzle 42 issupposed to be at such a distance from the cam that edge 46 and the camare in the contraction zone of the air jet, and if, at the same time,the feed air pressure in capsule 51 is such that the membrane of saidcapsule drives the nozzle to the considered position, and if, in suchconditions, the current flowing through the galvanometer increases anddrives the cam in such a manner that the distance between said cam andthe nozzle orifice is increased, the reaction of the cam on the airpressure in the system formed by nozzle 42 and capsule 51 will decrease;as the said pressure de- I creases, capsule 51 will grow thinner, lever43 will be driven downwards and the nozzle will be brought nearer to cam46, until the distance between both members is so small that thereaction of the cam on the air jet and consequently on the air pressurein the system again assumes its former value, the balance of the systembeing recovered. The displacements of lever 43 may be used, beingsuitably amplified, for transmitting every indication, registering,regulating correlated to the intensity changes of the current flowingthrough meter 48.

Fig. 9 shows the invention as applied to measuring variations in thelength of a hair or a silk-worm thread 56, due to variations in thedampness of air. The hair is fastened at one end to a fixed point and atits other end to an unextensible thread 57 wound on a small diameterpulley 58 keyed on a shaft 59, pivoted on points to a fixed support 62.On shaft 59 is mounted a spiral recoil spring 63, holding hair 56slightly taught, and an end cam 64 the edge of which cooperates with anozzle 65 having a thin walled orifice and projecting an air jet on edge64 of the cam. The nozzle is mounted on a balance lever 66, 67os'cillable on a shaft 68 in bearings 69, 69. Nozzle 65 is connectedthrough a flexible hose 70, to bellows 71 solid with a fixed support 72.A push-rod 73, carried on the lower face of the bellows, presses on arm67 of the balance lever. Air under pressure is fed through duct 74,provided with regulating valve 75, to nozzle 65 and bellows 71.

If hair 56 is supposed to be balanced by the tension of spring 63 andthe upper edge of cam 64 opposite nozzle 65 to be located within thecontraction zone of the air jet flowing out of said nozzle, if moreoverin such a position of the above-named members, the air pressureregulated by valve 75 is supposed to be such that the reaction againstthe cam of the air jet on nozzle 65 repulses the latter upwards due toan elongation of the air, by increasing the distance between the nozzleand the cam, the pressure will be made to decrease within and behind thenozzle and consequently the pressure will also decrease within thebellows. Arm 67 of the balance lever will move upwards and will thuslower the nozzle until the latter assumes a new balance positioncorresponding to the amount by which the hair was elongated.

There may be derived from balance lever 66, 67, an actuating motion,with possible amplification, for an indicating or registering devicewhich will reproduce on large scale the expansions or contractions ofthe hair.

In the case of the device shown in Fig. 10, a galvanom: eter 76 rotatesan end cam 77, opposite to which is located a nozzle 78 the outletorifice of which delivers an air jet under pressure, said nozzle beingnormally at such a distance from the cam that the upper face of thelatter is in the contraction zone of an air jet escaping through saidnozzle. The nozzle is mounted on an arm 79 rotatable about a shaft 80 ona fixed support 81. This support carries bellows 82 provided with apush-rod 83, pressing on lever 79. The latter carries, through an arm84, another nozzle 78a, for instance with a thin walled orifice,cooperating with a shutter 85 mounted on a membrane 86 of a capsule 87which is also supported on arm 79. A spring 88 strives to move membrane86 aside from nozzle 78a. A compressed air duct 89 feeds, throughregulating valve 90, partly flexible pipe 91 and constriction 92, nozzle78 and capsule 87 and, through pipe 93, provided with a constriction 94,and pipe 95, bellows 82. It feeds also, through partly flexible pipe 96,nozzle 78a.

The device being balanced, if the edge of cam 77 being rotated by arotation of the frame of galvanometer 76, is supposed to get nearernozzle 78, the pressure will increase very slightly in capsule 87 (a fewmillimeters water height for instance). Membrane 86 is then repulsed andcloses nozzle 78a, against the action of spring 88. The pressureincreases in bellows 82 which expand and drive nozzle 78 away from cam77 up to the point where, the leakage at the nozzle becoming sufficient,shutter 85 is driven away from nozzle 7 8a, whence there is recovered aleakage, the amount of which is equal to that of the compressed airbrought in through constriction 94, whence a new balance of the deviceis attained. An opposite action of the edge of cam 77 would produceopposite actions and effects and the condition of balance would also berecovered.

The amplifying relay may either be fixed to arm 79 or be independent.Only the nozzle must in every case accompany arm 79.

In the latter case (Fig. 11) the pipe connecting nozzle 78 to capsule 87is flexible. The parts which are common to both devices (Figs. 10 and11) are designed by the same reference numbers. The operation is thesame in either case.

Fig. 12 shows the invention as applied to indicating and registering thevariations of a phenomenon resulting in a weak electric current, as wellas to controlling a regulating mechanism. Fig. 13 is a plan view of aportion of such a device.

in this apparatus the component elements of the apparatus shown in theother figures are again to be found, viz.: a galvanometer 97, an end cam98, a nozzle 99 with a thin walled orifice, a capsule 100 with amembrane 101 carrying a shutter 102 acting on a nozzle 103, possiblywith thin walled orifice, and provided with a compression spring 104.Bellows 105 control an arm 106, pivoted on a shaft 1060. Moreover, inthis apparatus there may be seen an index 107 solid with arm 106 and thetip of which moves before a graduated scale 108, as well as an arm 109carrying a registering style which traces on a rotating cylinder 111 anamplified registering of the variations of the phenomenon correspondingto the intensity variations of the current flowing through meter 97.Capsule 100, nozzle 103 and bellows 105 are fed with compressed airthrough duct 112 and branch pipes 113 and 114. A tension spring 115strives to constantly bring nozzle 103 nearer to shutter 102. On arm 107is hinged at 116 a connecting-rod 117 the other end of which is hingedat 118 on a lever 119 pivoted at 120 on a fixed support (not shown) andhinged at 121 on nozzle holder 122. Holes such as 123 in lever 119 makepossible, by threading shaft 118 in any one of the said holes, to varythe ratio of the arms of lever 119.

On the other hand, there is hinged on shaft 106a a lever 124 throughwhich extends a threaded rod 125, hinged at 126 on an arm 1-27 solidwith an arm 128, pivoted on shaft 105a. A spring 128a presses on arm 127and under a'rin 124. A milled knob 129 screwed on rod 125 allows to varythe relative angular position of arms 124 and 128. The lower end of arm123 carries a nozzle I30, possibly with thin walled orifice, cooperatingwith a shutter screen 131 mounted on a spring 132 fixed on a small arm133 solid with index 107. A stop 134 limits the displacement of screen131 towards nozzle 130.

Lever 124 carries an inclined vane 135 cooperating with a nozzle 13 6,possibly with thin walled orifice, through the agency of a key 137,mounted on a resilient arm 138 fixed to nozzle 136. The latter iscarried on the bottom of bellows 140 fed with compressed air through abranch pipe 141 derived from duct 112 and comprising a constr'iction141d. A spring 142 seated on a fixed support 143 opposes thedisplacements of the bottom 139 of said bellows 140.

On the other hand, bellows 144, fixed on support 14-3 are fed withcompressed air through a branch pipe 146 derived from duct 112. The saidbellows act by means of a push-rod 145, on lever 124. Branch pipe 146feeds also, through a partially flexible duct 147, nozzle 130.

There is also shown on this figure a valve 148 located in a compressedfluid duct 149 and controlled by means of'a resilient membrane 150 withcompression spring 151. This membrane 150 communicates through branchpipe 141 with main compressed air feed duct 112.

This device operates as follows:

The balance being assumed to be established for a certain value of theintensity of the current flowing through meter 97, and for this value ofsaid current the portion of edge 98 opposite the orifice of nozzle 99being supposed to lie in the contraction zone of the air jet issued fromnozzle 99 and also, in such a condition, shutter screen 102 of capsule100 being supposed to be located, under the etfect of the pressureprevailing within the capsule and of the force of spring 1194, withinthe contraction zone of the air jet issued from nozzle 103, in the casein which the orifice of the latter is thin walled, and in which index107 is opposite to a certain mark on scale 108; if then the currentflowing through the meter increases, cam 98 rotates on its shaft and itsedge is brought nearer to nozzle 99. The reaction exerted by the air jeton the nozzle will vary and will push the latter to the left of thedrawing, while the air pressure in capsule 11 5 will increase theshutter screen 102 will be consequently brought nearer to nozzle 103, upto the point where it will close it. There results a displacement of arm106 to the left of the drawing and consequently arm 107 will bedisplaced to the right, thus tensioning spring 115; Index 16 7 moving tothe right of the drawing, connecting rod 117 rotates lever 119 whichseparates nozzle 99 from the cam until, the reaction of the jet onnozzle 99 being thus decreased and the pressure decreasing behind saidnozzle, the pressure within capsule is also decreased and a new state ofbalance is established in the system, due to the leak caused at nozzle103. After this balance is attained, the device stops and index 107gives, on scale 108 a new indication corresponding to the new intensityof the electric current through the meter, this intensity valuecorresponding to a new condition of the phenomenon determining theintensity of said current.

Through displacing hinge point 118 of connecting rod 117, the ratio ofdisplacements of index 107 and nozzle 99 can be varied.

Arm 109 forming an extension of index 107 registers, as a diagram a, thevariations of the considered phenomenon.

Supposing regulator 148, 150, 151 to be at its middle position, and thatfor this middle position lever 124 is also at its middle position, andthat nozzle 13-0 and cam 98 and screens 131 and 137 are at respectivepositions such that said screens are in the middle contraction zone ofthe air jets issued from said nozzles and also that bellows 105, 140 and144 are at their middle positions, and supposing also that a variationof the phenomenon to be re ulated increases the intensity of the currentthrough meter 97; bellows 105 within which the pressure increases,pushes lever 106 to the left of the drawing and, displacing screen 131to the right, releases nozzle and decreases the air pressure withincapsule 100. This pressure decrease is transmitted to bellows 144 whichlower lever 124 and bring nozzle 130 nearer to screen 131 until a newbalance condition is established, corresponding to the new conditionsought for, of the phenomenon to be regulated. The vane, which in thiscase is made inclinac-le, is brought to press on screen 135 and causesthe shutting of nozzle 136,- and consequently an increase of pressure incapsule 140, said increase of pressure being converted into adisplacement from right to left of wall 139, up to the point where, dueto the inclination of edge 135, the leakage corresponding to the balancecondition is reestablished, device 136, 137, 138, 139, stops for aninternal pressure higher than before, due to the opposed spring 142contracting. This new pressure value is transmitted through duct 141 tovalve 148 causing the partial or total formation of orifice 148.

if the variation of the phenomenon to be regulated occurs in theopposite direction, all actions in the device will also occur in theopposite direction.

Through acting on milled knob 129, it is possible to control thevariation of the position of nozzle 130 with relation to arms 196, 107and consequently of the medium regulating point.

instead of being shaped as an end cam, the screen may also be shaped asa cam the edge of which cooperating with the nozzle is parallel in eachof its active portions to the axis of rotation of said cam.

in the case in which an end cam is used the skews which it comprises maybe given such a shape that the generatrix of said skews always extendsthrough the rotation pivot of the cam.

Though only a few embodiments of the present invention have beendescribed and illustrated, it is to be understood that manymodifications may be used within the scope of said invention as definedin the following claims.

What we claim is:

l. in a gaseous fluid relay, a nozzle having a thin end wallperpendicular to the axis of the nozzle and provided with a jet orificeaxially thereof smaller than the diameter of said end wall whereby afluid jet issuing from said nozzle will have a zone of maximumcontraction spaced outwardly from said orifice, a conduit supplyinggaseous fluid to said nozzle, and a movable screen adjacent to and infront of said nozzle.

2. A device constructed in accordance with claim 1 wherein said screennormally has a portion within the contracted zone of said fluid jet.

3. A gaseous fluid relay comprising a nozzle having a thin end wallperpendicular to the axis of said nozzle and provided axially thereofwith a jet orifice smaller in diameter than said end wall whereby theissuing fluid jet from said orifice will have a zone of maximumcontraction spaced outwardly from said orifice, a conduit supplyinggaseous fluid to said nozzle, a movable screen adjacent to and in frontof said nozzle, and screen-actuating means responsive to a variablebehavior phenomenon, operatively connected to said screen for varyingthe distance of said screen from said nozzle. 7

4. A device constructed in accordance with claim 3 provided with controlmeans responsive to variations in pressure in said conduit occurringincident to variations in the distance of said screen from said nozzle.

5. A device constructed in accordance with claim 3 wherein said screennormally has a portion within the contracted zone of said fluid jet.

6. A gaseous fluid relay comprising a nozzle having a thin end wallperpendicular to the axis of said nozzle and provided axially thereofwith a jet orifice smaller in diameter than said end wall whereby theissuing fluid jet from said orifice will have a zone of maximumcontraction spaced outwardly from said orifice, a conduit supplyinggaseous fluid to said nozzle, a movable screen adjacent to and in frontof said nozzle, screen-actuating means responsive to a variable behaviorphenomenon, operatively connected to said screen for varying thedistance of said screen from said nozzle, means for supporting saidnozzle for movement toward and away from said screen, and meansresponsive to variations in pressure in said conduit occurring incidentto variations in the distance of said screen from said nozzle for movingsaid support to move said nozzle toward and away from said screen.

7. A gaseous fiuid relay comprising a nozzle having a thin end wallperpendicular to the axis of said nozzle and provided axially thereofwith a jet orifice smaller in diameter than said end wall whereby theissuing fiuitl jet from said orifice will have a zone of maximumcontraction spaced outwardly from said orifice, a conduit supplyinggaseous fluid to said nozzle, a movable screen adjacent to and in frontof said nozzle, screen-actuating means responsive to a variable behaviorphenomenon, operatively connected to said screen for varying thedistance of said screen from said nozzle, a pivoted arm carrying saidnozzle, an expansible chamber device communicating with said conduit tobe expanded and contracted in accordance with variations in pressure insaid conduit, and an arm rigid with said pivoted arm and engaging saidexpansible chamber device.

8. A gaseous fluid relay comprising a nozzle having a thin end wallperpendicular to the axis of said nozzle and provided axially thereofwith a jet orifice smaller in diameter than said end wall whereby theissuing fluid jet from said orifice will have a zone of maximumcontraction spaced outwardly from said orifice, a conduit supplyinggaseous fluid to said nozzle, a movable screen adjacent to and in frontof said nozzle, an arcuate member fixed at one end and connected at itsother end to said screen and subject to deformations to move said screentoward and away from said nozzle, and means subject to variations inpressure in said conduit incident to variations in the distance of saidscreen from said nozzle for moving said nozzle toward and away from saidscreen.

9. A device constructed in accordance with claim 8 wherein the means formoving said nozzle comprises an expansible chamber device communicatingwith said conduit and having mechanical connection with said nozzle.

10. A device constructed in accordance with claim 8 wherein the meansfor moving said nozzle comprises a pivoted supporting arm for saidnozzle, a bellows communicating with said conduit to be expanded orcontracted in accordance with pressure variations in said conduit, oneend of said bellows being fixed and the other end being movable, and anoperating arm fixed to said pivoted arm and engaging the movable end ofsaid bellows.

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